Blade shroud template



Dec. 8, 1942. E. w. BoNNEss BLADE sHRoUD TEMPLATE Filed March 20, 1942 emm .1@ /l Patented Dec. 8, 1942 UNITED STATES BLADE SHRO'UDl TEMPLATE Application March 20, 1942, Serial No. 435,483

(Cl. S90- 62) 8 Claims.

This invention relates generally to turbine blading and more particularly to apparatus for use in locating and forming blade tenon receiving apertures in a shroud strip adapted to be riveted, welded or otherwise secured to blades provided with tenoned ends.

In this connection, a common practice has been (1) to punch or otherwise form uniformly spaced tenon receiving holes in the shroud strip, (2) to place and hold the apertured shroud strip on the tenonedends of the blades with the tenons projecting through the apertures therein, (3) to bring together and secure the bases or root portions of the blades in their proper row forming relation, and (4) `to peen over the exposed portions of the tenons, thereby riveting the shroud strip to the tips of the blades. Another common practice has been (1) to assemble and secure the blades in their proper row forming relation, (2) to place the shroud strip on the tenoned ends of the blades and scratch or otherwise mark the shroud strip at the points the tenon receiving holes are to be formed therein, (3) to punch or otherwise form the tenon receiving holes in the shroud strip in accordance with said markings, (4) to'pla'ce the apertured shroud strip on the tenoned ends of the blades with tenons projecting through the apertures therein, and (5) to peen over the exposed portions of the tenons, thereby riveting the shroud strip to the tips of the blades.

The rst mentioned procedure is objectionable since the spacing oi the blade bases or root portions is not absolutely uniform, i. e., variations of several thousandths of an inch are common, and as a result many blade failures are directly attributable to the initial stressing of the blades produced by the retention of the tenons in the uniformly spaced shroud apertures. The second mentioned procedure is also objectionable since errors of several thousandths of an inch occur in locating and forming the tenon receiving holes in the shroud strip and as a result the ends of some of the blades must be flexed in order to place the shroud strip on the ends of the blades with the tenons projecting through the tenon receiving holes formed in the shroud strip. Consequently, the second mentioned procedure also subjects the blades to an initial stressing action which in many instances results in blade failures during normal operation.

It is therefore an object of this invention to provide an improved apparatus which can be readily applied to the tenoned ends of a group of f positioned blades, i. e. blades assembled in a predetermined row forming relation, and which can be then readily manipulated to determine the exact spaced relation existing between the tenons on the blades in said group.

Another object of this invention is to provide an improved apparatus which accurately determines-the spaced relation existing between the tenons on a group `of positioned blades and which can be then applied to a shroud strip and used as a hole forming template operable to locate the tenon receiving holes in the shroud strip in exact conformity with the tenons on the blades in said group. v

Still another object of this invention is to provide an improved, inexpensive apparatus which requires only a vminimum degree of skill in order to locate and form the blade tenon receiving apertures in a shroud strip to be applied to a group of positioned blades having tenons thereon.

The invention accordingly consists of the various features of construction, combinations of elements, and arrangements of parts as is more fully set forth in the appended `claims and in the detailed description, in which:

Fig. 1 is a side elevation of a group of positioned blades having a shroud member riveted to the tenoned ends of the blades;

Fig. 2 is a plan view of the blade group shown in Fig. 1;

Fig. 3 is a section taken on line III-III of Fig. 1;

Fig. 4 is a plan View of the preferred form of apparatus for use in locating and forming the tenon receiving apertures in a shroud member;

Fig. 5 is a partial section illustrating the vapparatus shown in Fig. 4 applied to the tenoned ends of a group of positioned blades;

Fig. 6 is a partial plan View of theV structure shown in Fig. 5;

Fig. '7 is a partial section taken on line VII-VII of Fig. 6;

Fig. 3 is a partial side elevation of ture shown in Fig. 6; l

Fig. 9 is a partial plan View illustrating the relative positions of the bars and tenons;

Fig. 10 is a View similar to Fig. 7 illustrating a modication in the manner of applying the yapparatus to the tenoned ends of the blades;

Fig. 11 is a plan View illustrating the apparatus shown in Fig. 4 clamped against the top side of an imperforate shroud member; and

Fig. 12 is an end View of the structure shown the strucinclusive, and a bar 6 for each tenoned bladepositionable to extend transversely across said strip and each bar having therein an opening 'I substantially conforming with the shapeV of a tenon as it appears in a plan view thereof. The opposite ends of each bar 6 are provided with a bore il which extends therethrough between' pairs of raised parallel projections 9 and I I provided on the upper and lower opposite end surface portions of each bar (see Figs. 6, 7 and 8) and a pair of blocks I2 are removably secured to the underside of the opposite ends of each bar between the projections II by means of cap screws I3 which extend through the bores 8 and into the internally threaded bores I4 provided in the blocks I2. Each block I2 extends inward toward the aperture .'I in the bar a considerable distance beyond the inner ends of the projections II (see Fig. 7) and inner marginal bottom portion of each block is recessed to provide a shroud 'member engaging shoulder I5, The top surface of each block is beveled as indicated by numeral I6, Fig. 8, to permit arcuate exing of the strip I which has its opposite edge portions disposed between the top surfaces of the blocks I2 vand the opposed underside surface portions of the bars 6 inward of the projections II. In other words, the flexible strip I is held against the underside of the bars 6 with its opposite edges abutting the inner edges of the projections I I by means of the blocks I2 which extend beneath and supportingly engage the underside marginal portions of the strip I. The cap screws E3, when tightened, securely clamp the bars 6 to the strip I and, when loosened, permits the bars 6 to be selectively moved longitudinally of the strip. Stated differently, vthe bars '6 and strip I areY interconnected for relative movement and when thus interconnected may be positioned as a unit on the tenoned ends of a group of positioned blades as indicated in Fig. 5.

of a group of positioned and substantially rigid blades. In this connection, it is preferable to first position and clamp the middle bar to the strip I with the tenon on the underlying blade disposed centrally within the aperture 'I therein and to then alternately position and clamp the remaining bars on opposite sides of the mid,- die bar with the tenons on the underlying blades engaging the middle bar sides of the apertures I in the remaining bars in the manner shown to an exaggerated degree in Fig. 9 as this pro- "cedure permits the use of apertures 1 more nearly 'conforming with the shape of a tenon as it appears in an end view thereof.

If the tenoned ends of a group of positioned blades can ber slightly exed,then the apertures in the b ars l6 can be made in exact conform- Aance with the shape of a tenon as it appears in an end view thereof since the clamped assembly comprising the' strip I and bars 6 can be readily removed from the `radially diverging tenoned ends of a group of positioned blades simply by appropriately'flexingV same. In this connection, it is preferable, in order to obtain a high degree of accuracy when using relatively thick shroud members, to correctly locate theY holes or apertures in an arcuately bent shroud member with respect to the radius of curvature at its center, i, e., at arpoint midway between its top and bottom surfaces. This can be'readily accomplished simply by spacing the underside of the extremely thin strip I from the ends of the blades from which the tenons project a dis- The strip I and the bars 6 are preferably applied to the tenoned ends of a group of positioned blades as shown in Fig. 5 by first assembling the bars on the strip I with the aperture 'i Yin each bar overlying one of the apertures 2 in the strip I (see Fig. 4), then placing the assembly on the tenoned ends of the blades with the apertures 2 in the strip I disposed ,in tenon receiving relation with respect to the'ends of said blades, then moving the bars relative to the strip until the aperture 'I in each bar receives the tenon on the underlying blade, and then proceeding to tighten the cap rscrews I3 on each bar, thereby securely clamping each bar to the strip I withV the tenon on the underlying blade entering the aperture 'I in the overlying bar. The apertures Iinthe bars 6, although substantiallyconforming with the shape of a tenon as it appears in an end view thereof, are necessarily made a trifle larger than the tenons in order to permit the removal of the clamped assembly fromV the radially diverging tenoned ends tancev approximately equal to half the thickness of the shroud member `as is indicated in Fig; 10 which clearly shows such a spacing means I'I interposed between andengaging the underside of the strip I and the opposed end of the blade 4. This assembly vcan be readilyapplied to the tenoned ends of a group of positioned blades in the manner described in the preceding paragraph, the only difference being that Vthe spacing means I1, depending on itsnature, be placed to assume the position shown in Fig. 10 either before or after the assembly comprising the strip I and the bars 6 are positioned on the ends of the blades. Obviously, if said assembly is first positioned on the tenoned ends of the blades, the spacing means must' be inserted before the bars 6 are immovably clamped to the l an integral top portion 23 presenting a top sur-Y face having adjacent each side edge thereof-a coextensive upstanding flange v24 and having formed therein between saideangesthree coextensive recesses 26, 21- and 28 which extend in spaced parallel relation with respect to each other and with respect to the flanges 24. The recesses 26 and 28 are identical and each includes an enlarged bolt head receiving llower portion designated 29 and 3|, respectively. The recess 21, which isdisposed midway between the flanges 24 andmidway between the recesses 26 and 2.8,

has a central portion 32 of increased depth' as is clearly shown in Fig. 12. The width of the top portion of the recess 2'! conforms with the length of the bars 6 and the preferable procedure to be followed in positioning and clamping the assembly, which comprises the relatively immovf able strip I and the bars 6, to the shroud member I8 is to first place and hold the shroud member against the shoulders I presented by the inner marginal bottom portions of the blocks I2, then to place the unit comprising the assembly and the shroud member in the recess 2'I (see Fig. 12) and then to securely clamp the unit to the top portion 23 of the table I9 by any suitable means such as the members 33 shown in Figs. 11 and 12'. The members 33 each comprises an elongated rigid bar 34 adapted to extend across a fiange 24 and the top of the cap screw I3 on the near end of the adjacent bar 6 and a bolt 36 which extends through a bore 31 in the bar 34 intermediate the ends thereof and which has a head 38 disposed in the enlarged portion 29 or 3I of the recesses 26 and 28, respectively. The bars 34 are each provided with a depending outer end portion which is adapted to engage the outside surface of a ange 24 to prevent the bar from turning when the bolt 36 is being tightened. The clamping members are assembled on the table I9 by inserting the bolt heads 38 at the ends of the recesses 26 and 28 and moving them therealong to desired positions. When the bars 34 span the flanges 24 and the cap screws I3 as shown, the tightening of the bolts 36 securely clamps the unit comprising-the bars 3, strip I and shroud member Iii to the table I9. In this connection, the marginal recess forming the shoulder I5 on the blocks I2' should be made lequal to or slightly less than the thickness of the shroud member, as shown in Fig. l2, in order to effect the necessary clamping action. Obviously, before the clamping members 33 are tightened, relative movement between the assembly, which comprises the relatively immovable strip I and bars 6, and the shroud member I8 should be effected when necessary to correctly position same.

The tenon receiving apertures 39 can now be readily formed in the shroud member I8 in conformance with the spacing of the tenons on the group of positioned blades simply by inserting a suitable cutting tool 4Iv through the aperture 'I in the bar 6 which now functions as a template to guide the cutting tool and thereby form an aperture in the underlying shroud member which conforms exactly with the aperture 'I in the bar 6. In forming the apertures 39 in the shroud member I8 with the milling type of cutter shown, either the cutting tool 4I or the table I9 may be moved in accordance with the usual practice and by any suitable means (not shown) in order to obtain exact conformance between the aperture 39 and the overlying aperture 'I in the bar 6. When the forming of the apertures 39 in the shroud member has been completed, the clamping members 33 are loosened, the assembly and shroud member removed from the table I9 and separated, and the shroud member I3 arcuately bent, by a suitable means (not shown), for positioning said member on the tenoned ends of the same group of positioned blades on which the assembly comprising the strip I and bars 6 were placed and rendered relatively immovable prior to their removal therefrom as previously described. Obviously, the apertured and arcuately bent shroud member can now be readily placed on the tenoned ends of said same group of positioned blades (the procedure being merely the reverse of that specified for effecting the removal of said assembly) and the ends of the tenons peened over to produce the shrouded structure 42 shown in Figs. 1-3, inclusive.

The use of the apparatus hereinbefore described enables apertures to be formed in a shroud member in exact conformance rwith the spacing of the tenons on a group of positioned blades and it should therefore be obvious that a shroud member, when apertured with the aid of said apapratus, can be readily placed on and secured to the tenoned ends of said group of .blades without initially stressing same. Apparatus embodying the invention is applicable to all types of tenoned blades and it should be understood that the apparatus herein shown and described is solely for purposes of illustration and that it is not desired to limit the invention to the exact details of construction herein shown and described, as various modifications within the scope of the appended claims may occur to persons skilled in the art.

. It is claimed and desired to secure by Letters Patent:

1. Apparatus for use in locating and forming tenon receiving apertures in a shroud member for a group of positioned blades having tenons thereon comprising an apertured bar for each tenoned blade juxtapositionable in tenon receiving relation to the end thereof, an elongated flexible' member juxtapositionable in arcuately flexed relation to the tenon ends of said blades, and means interconnecting said bars and flexible member for relative movement and for immovably securing said bars to said member.

' 2. Apparatus for use in locating and forming tenon receiving apertures in a shroud member for a group of positionedfblades having tenons thereon comprising a bar for each tenoned blade,

said bars each having therein an aperture substantially conforming with the shape of a tenon as it appears in an end view thereof, an elongated flexible member juxtapositionable in arcuately exed relation to the tenon ends of said blades, and means interconnecting said bars and flexible member for relative movement and for immovably securing said bars to said member.

3. Apparatus for use in locating and forming tenon receiving apertures in a shroud member for a group of positioned blades having tenons thereon comprising a substantially rigid bar for each tenoned blade, said bars each having therein an aperture substantially conforming with the shape of a tenon as it appears in an end view thereof, an elongated flexible member juxtapositionable in arcuately exed relation to the tenon ends of said blades, and means for interconnecting said bars and flexible member to render said bars positionable in spaced relation longitudinally of said flexible member with each bar having its aperture disposed in tenon receiving relation with respect to a one of said blades and to render said bars and flexible member relatively immovable.

4.V Apparatus for use in locating and forming tenon receiving apertures in a shroud member for a group of positioned blades having tenons thereon comprising an elongated thin flexible strip juxtapositionable in arcuately flexed relation to the tenon ends of said blades, a bar for each tenoned blade positionable to extend transversely of said strip and each bar having therein an aperture substantially conforming with the shape of a tenon as it appears in an end view,

and means for interconnect-ing said bars and.

strip to render'said bars positionable in spaced relation longitudinallyof said strip with each bar having itsaperture in tenoni receiving relation with respect to. a'on'e of said` blades and to render said bars and strip relatively immovable. 5. Apparatus for use in locating and forming tenon receiving apertures in a shroud member for a group of positioned blades Yhaving tenons thereon comprising e an elongated,Y thin flexible base strip positionable in arcuately exed relation on the tenon endsV of said blades with a portion of each tenon projecting therebeyond, a bar for each tenoned blade positonable to extend transversely of said strip and each bar having therein an aperture substantially conforming with the shape of a tenon as it appears in an end view thereof, and means interconnecting said bars and strip for relative movement and for immovably securing said bars to said strip.

6. Apparatus for use in locating and forming tenon receiving apertures in a shroud member for a group of positioned blades having tenons lthereon comprising an elongated, thin, flexible base strip positionable in arcuately flexed relation on 'the tenon ends of said blades with a portion of each tenon projecting therebeyond, a bar for each tenoned blade' positionable to extend transverselyvorf said strip and each bar having therein'an` aperture substantially conforming with the shape of atenon as it appears in an end view thereof,` and Vmeans for interconnecting said bars and vstrip to render same relatively movable and positionable as a unit on the tenon ends of said blades and to render said bars and strip relatively immovable.

'7. Apparatus for use in locating and forming Vtenon receiving `apertures in a shroud member for a group of positioned blades having tenons thereon comprising an elongated. thin, apertured, exible base strip positionable in-arcuately Y flexed relation on the tenon ends ofV said blades With a portion of each tenon projecting therethrough, a bar for each tenoned blade positionable to extend transversely of said strip and each bar having therein an aperture substantiallyi y, conforming with the shape of a tenon as it appears in an end view thereof, and. means for interconnecting said bars and strip to render same relatively movable and positionable ras a unit on the tenon ends of said blades and `to render said bars and strip relatively immovable.

8. Apparatus for use inv locating and forming tenon receiving apertures ina shroud member for a group of positioned blades having tenons thereon comprising an elongated flexible strip having va thickness materially less than the length of the tenons on said blades and having therein a longitudinal series of apertures conforming in number and arrangement but being` materially larger than the tenons on said blades,

a bar for each tenoned blade positionable to extend transversely of said strip in spaced relation longitudinally of the strip and each ybar having therein an aperture substantially conforming with the shape of a tenon as it appears in an end View thereof, and means interconnecting,

said bars and strip for positioning same as a unit on the tenoned ends of said blades with each aperture in said strip receiving a tenon on oneV of said blades and for rendering said bars and strip relatively movable to position each'bar on said strip with its aperture in tenon receiving relation with respect to the tenon projecting through the adjacent aperture in said strip, said interconnecting means -including parts yfor immovably securing said bars to said strip.

' ERNEST W. BoNNEss. 

